Dual stage accelerator assembly with pedal feedback system

ABSTRACT

A dual stage accelerator pedal assembly is provided that is capable of communicating various vehicle operating conditions to the driver as well as notifying the driver of a critical operating condition, such as a low battery pack level, via a change in pedal resistance. The change in pedal resistance is achieved by preloading one of the springs in the accelerator pedal&#39;s spring assembly. The spring assembly uses two springs exhibiting different spring force to achieve distinguishable first and second pedal stroke stages.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of U.S. patent application Ser. No.14/231,811, filed 1 Apr. 2014, the disclosure of which is incorporatedherein by reference for any and all purposes.

FIELD OF THE INVENTION

The present invention relates generally to a vehicle and, moreparticularly, to the design and configuration of an accelerator pedalmechanism that provides the user with feedback relating to vehicleoperating conditions.

BACKGROUND OF THE INVENTION

In a conventional vehicle utilizing an internal combustion engine (ICE),the functioning of the accelerator pedal is quite straightforward.Specifically, and assuming a level road surface, when the user pressesdown on the accelerator pedal the car accelerators; when the usermaintains the accelerator pedal in a particular location the car speedremains steady; and when the user releases pressure on the acceleratorpedal the car decelerates, the rate of deceleration depending on whetheror not the engine is in gear.

In typical hybrid and electric vehicles, when the user applies pressureto the brake pedal a regeneration system generates electricity that isused to recharge the vehicle's battery pack. Additionally in someelectric vehicles, both hybrid and all-electric vehicles, when the usereither completely releases pressure from the accelerator or simplyreduces the force applied to the accelerator indicating the driver'sdesire to decelerate, the vehicle is configured to apply regenerativebraking, thereby helping to recapture energy and partially recharge thebattery pack while slowing the car. Some drivers, however, find itunnerving for the regeneration system to be applied while they stillhave their foot on the accelerator pedal, especially if the regenerationsystem is applied aggressively. At least in part, this reaction may bedue to the differences felt by the driver when regenerative braking isapplied versus the deceleration of a conventional, ICE-based vehicle.

Accordingly, what is needed is an accelerator pedal mechanism that helpsalleviate the discomfort felt by some drivers during deceleration of anEV, preferably while providing useful feedback to the driver. Thepresent invention provides such an accelerator pedal mechanism.

SUMMARY OF THE INVENTION

The present invention provides a dual stage accelerator assembly thatcommunicates different operating conditions to the driver, as well asnotifying the driver of a critical operating condition via a pedalfeedback system. The system is comprised of an accelerator pedal and aspring assembly coupled to the accelerator pedal by an acceleratorlinkage arm. The spring assembly is comprised of (i) a first spring,(ii) a first spring compression member coupled to the linkage arm andproximate to a first end of the first spring, (iii) a second spring,(iv) a second spring compression member interposed between the secondend of the first spring and the first end of the second spring, (v) arear spring support member proximate to the second end of the secondspring, where the rear spring support member may be positioned in atleast a first position and a second position, where the support memberin the second position increases the preload compression applied to thesecond spring compared to the first position, and where the supportmember in the second position increases accelerator pedal resistancecompared to the first position, (vi) an adjustment mechanism coupled tothe rear spring support member which moves the support member to thefirst position upon receipt of a first control signal and moves thesupport member to the second position upon receipt of a second controlsignal, and (vii) a preload adjustment controller configured to transmitthe first and second control signals to the adjustment mechanism. Thefirst spring and the second spring may each be comprised of acompression coil spring. Preferably the spring force associated with thefirst spring is less than the spring force associated with the secondspring. One or more positioning members (e.g., a rod) may couple theadjustment mechanism to the rear spring support member. The adjustmentmechanism may be comprised of an electro-mechanical system (e.g., anelectric motor) or a pneumatic positioning system. An accelerator pedalstop, which may be integrated within the spring housing, may be used tolimit accelerator pedal travel.

In one aspect of the invention, the system may further include a batterymanagement system coupled to the vehicle's battery pack and to thepreload adjustment controller, where the battery management systemmonitors at least one characteristic of the battery pack. Monitoredcharacteristics may include current battery pack capacity, availabledriving range based on current battery pack capacity, and currentbattery pack temperature. The preload adjustment controller may beconfigured to transmit the first control signal to the adjustmentmechanism when the monitored characteristic is within a preset range,and the second control signal to the adjustment mechanism when themonitored characteristic is outside of the preset range. The preloadadjustment controller may also be configured to transmit a third controlsignal to the adjustment mechanism when the monitored characteristicfalls below a preset level, in which case the adjustment mechanism movesthe rear spring support member to a third position intermediate betweenthe first and second positions. The preset range may be input by thevehicle manufacturer or input via a user interface coupled to thepreload adjustment controller.

In another aspect, the system may further comprise (i) a regenerationsystem coupled to the vehicle's battery pack and configured to rechargethe battery pack when activated, (ii) a pedal stroke sensor whichmonitors accelerator pedal travel and detects an initial stage ofaccelerator pedal travel corresponding to a first pedal stroke stage anddetects a final stage of accelerator pedal travel corresponding to asecond pedal stroke stage, and (iii) a regeneration system controllercoupled to the pedal stroke sensor and to the regeneration system, wherethe regeneration system controller is configured to activate theregeneration system during the first pedal stroke stage and deactivatethe regeneration system during the second pedal stroke stage. Preferablyduring the second pedal stroke stage the vehicle battery pack iselectrically coupled to the vehicle's propulsion motor. The regenerationsystem controller may be configured to deactivate the regenerationsystem after completion of the first pedal stroke stage and prior toinitiation of the second pedal stroke stage. Preferably during pedalmotion within the first pedal stroke the first spring compression membermoves and the second spring compression member remains stationary, whilepedal motion within the second pedal stroke causes both the first andsecond spring compression members to move.

A further understanding of the nature and advantages of the presentinvention may be realized by reference to the remaining portions of thespecification and the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

It should be understood that the accompanying figures are only meant toillustrate, not limit, the scope of the invention and should not beconsidered to be to scale. Additionally, the same reference label ondifferent figures should be understood to refer to the same component ora component of similar functionality.

FIG. 1 provides a block diagram of the primary components, assembliesand subsystems used in at least one embodiment of the invention;

FIG. 2 illustrates the relationship of the accelerator spring assemblyto the pedal in one embodiment of the invention;

FIG. 3 provides a cross-sectional view of an accelerator spring assemblyin accordance with a preferred embodiment;

FIG. 4 illustrates the same accelerator spring assembly shown in FIG. 3after the spring has been preloaded;

FIG. 5 illustrates the same accelerator spring assembly shown in FIGS. 3and 4 with the spring preloaded to an intermediate level;

FIG. 6 provides a block diagram of the primary components, assembliesand subsystems as shown in FIG. 1, modified to include a regenerationsystem;

FIG. 7 illustrates the system shown in FIG. 6, modified to include auser interface;

FIG. 8 provides a cross-sectional view of an accelerator spring assemblyin accordance with an alternate preferred embodiment;

FIG. 9 illustrates the same accelerator spring assembly shown in FIG. 8after the spring has been preloaded;

FIG. 10 provides a cross-sectional view of an accelerator springassembly in accordance with an alternate preferred embodiment;

FIG. 11 illustrates the same accelerator spring assembly shown in FIG.10 during first stage spring compression;

FIG. 12 illustrates the same accelerator spring assembly shown in FIG.10 during second stage spring compression;

FIG. 13 illustrates the same accelerator spring assembly shown in FIG.10 after adjustment of the first/second stage transition point;

FIG. 14 illustrates the system shown in FIG. 6, modified to include astage transition controller;

FIG. 15 provides a cross-sectional view of an accelerator springassembly in accordance with an alternate preferred embodiment;

FIG. 16 illustrates the same accelerator spring assembly shown in FIG.15 after preloading of the first spring;

FIG. 17 illustrates the same accelerator spring assembly shown in FIG.15 after preloading of the second spring;

FIG. 18 illustrates the same accelerator spring assembly shown in FIG.15 after preloading of both the first and second springs;

FIG. 19 illustrates the system shown in FIG. 6, modified to include apair of spring load adjustment controllers;

FIG. 20 illustrates the system shown in FIG. 7, modified to include apair of spring load adjustment controllers;

FIG. 21 provides a cross-sectional view of an accelerator springassembly in accordance with an alternate preferred embodiment;

FIG. 22 illustrates the same accelerator spring assembly shown in FIG.21 after adjustment of the first/second stage transition point andpreloading of the first spring;

FIG. 23 provides a cross-sectional view of an accelerator springassembly in accordance with an alternate preferred embodiment;

FIG. 24 illustrates the same accelerator spring assembly shown in FIG.23 after adjustment of the first/second stage transition point andpreloading of the second spring;

FIG. 25 provides a cross-sectional view of an accelerator springassembly in accordance with an alternate preferred embodiment;

FIG. 26 illustrates the same accelerator spring assembly shown in FIG.25 after adjustment of the first/second stage transition point andpreloading of both the first and second springs;

FIG. 27 provides a cross-sectional view of an accelerator springassembly in accordance with an alternate preferred embodiment;

FIG. 28 illustrates the same accelerator spring assembly shown in FIG.27 after the accelerator pedal has been partially depressed;

FIG. 29 illustrates the system shown in FIG. 6, modified to include apedal preload controller suitable for use with the accelerator springassembly shown in FIGS. 27-28; and

FIG. 30 illustrates the system shown in FIG. 29, modified to include auser interface.

DESCRIPTION OF THE SPECIFIC EMBODIMENTS

As used herein, the singular forms “a”, “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. The terms “comprises”, “comprising”, “includes”, and/or“including”, as used herein, specify the presence of stated features,process steps, operations, elements, and/or components, but do notpreclude the presence or addition of one or more other features, processsteps, operations, elements, components, and/or groups thereof. As usedherein, the term “and/or” and the symbol “/” are meant to include anyand all combinations of one or more of the associated listed items.Additionally, while the terms first, second, etc. may be used herein todescribe various steps, calculations, or components, these steps,calculations, or components should not be limited by these terms, ratherthese terms are only used to distinguish one step, calculation, orcomponent from another. For example, a first calculation could be termeda second calculation, and, similarly, a first step could be termed asecond step, and, similarly, a first component could be termed a secondcomponent, without departing from the scope of this disclosure. The term“battery pack” as used herein refers to one or more batterieselectrically interconnected to achieve the desired voltage and capacity.The terms “electric vehicle” and “EV” may be used interchangeably andmay refer to an all-electric vehicle, a plug-in hybrid vehicle, alsoreferred to as a PHEV, or a hybrid vehicle, also referred to as a HEV,where a hybrid vehicle utilizes multiple sources of propulsion includingan electric drive system.

FIG. 1 provides a block diagram of the primary components, assembliesand subsystems used in at least one embodiment of the invention. Asshown, attached to accelerator pedal 101 is the accelerator springassembly 103. It should be understood that the term “spring” as usedherein may refer to any of a variety of mechanisms that can be used toprovide resistance to the depression of pedal 101, although in thepreferred embodiment the spring is a mechanical spring, more preferablya compression spring, and still more preferably a coiled compressionspring. FIG. 2 illustrates the relationship of accelerator springassembly 103 to pedal 101 in one embodiment of the invention in whichthe pedal bracket 201 is hinged about hinge point 203.

As the driver depresses accelerator pedal 101, the degree to which thepedal is depressed is monitored by a sensor 105. Although sensor 105 ispreferably integrated into spring assembly 103, it may also be separatefrom assembly 103, for example coupled via a linkage arm to the bracket201 to which pedal 101 is mounted. The position of pedal 101, asdetected by sensor 105, is used by a motor control subsystem 107 tocontrol the speed of motor 109, and thus the speed of the vehicle. Thepower required to operate motor 109 is provided by the battery orbatteries within battery pack 111.

In a typical EV, a variety of battery pack characteristics areperiodically or continually monitored using a set of appropriatesensors, thus allowing the battery pack management system 113 todetermine the health of the battery pack as well as optimize batterypack operation. Some of the characteristics that may be monitoredinclude state-of-charge, temperature (both battery pack internaltemperature and individual battery temperature), current battery packcapacity, rate of charge, rate of discharge, number of charge cycles todate, battery pack pressure, battery pack humidity level, shortcircuits, open circuits, etc. Of these, the current battery packcapacity is of primary importance in determining how much further thecar can travel before the battery is drained. The rate of discharge,which varies with road slope, ambient temperature, battery age, rate ofacceleration and in general how hard the car is being driven, is anotherimportant battery pack characteristic as the EV's remaining range willvary both with current battery pack capacity and the rate of discharge(e.g., current rate of discharge, average rate of discharge, etc.).

Due to the importance of the current battery capacity in determiningavailable driving range, a typical EV will provide several indicators ofthe current battery pack capacity and, in some instances, combine thatinformation in a display with the remaining vehicle range. Typicaldisplays provide some graphical representation of current battery packcapacity and/or remaining vehicle range; alternately, these values maybe provided digitally, for example by providing the percentage of theremaining battery pack capacity and/or the remaining vehicle range givenin terms of the number of miles or kilometers the car can still travelfor a given rate of discharge. Given the importance of this data alongwith the range anxiety felt by some EV drivers, this data is often colorcoded to emphasize dwindling battery capacity and/or available drivingrange. For example, from 50 to 100 percent capacity the data may becolor coded blue; then from 25 to 50 percent capacity the data may becolor coded yellow; and lastly from 0 to 25 percent capacity the datamay be color coded red.

While visual displays provide the driver with the necessary informationto schedule charging cycles and tailor driving habits to match availablebattery capacity, such displays often lead to increased, rather thandecreased, range anxiety as the driver focuses on the displayed data.Alternately, the driver may ignore the displayed information until theyare out of range of their preferred charging station. Accordingly thepreferred embodiment of the present invention can be used to provide theuser with a tactile indicator that the battery capacity has fallen belowa preset level.

FIG. 3 illustrates a preferred embodiment of an accelerator springassembly 300 in accordance with the invention. Within spring housing 301is a spring 303, where spring 303 is preferably comprised of acompression coil spring as shown. The accelerator pedal arm 201,attached at one end to pedal 101, passes into spring housing 301. Aportion of pedal arm 105, distal from pedal 101, is coupled to a springcompression member 305 such that as pedal 101 is depressed by thedriver, spring 303 is compressed within spring housing 301. As a result,the further the driver depresses pedal 101, the greater the forcerequired to overcome the force provided by spring 303. Although notrequired, preferably spring housing 301 includes a pedal stop 307 thatlimits the possible travel of spring compression member 305, therebylimiting how far pedal 101 may be depressed.

The front face of spring 303 rests against spring compression member 305while the rear face of spring 303 rests against a rear spring supportmember 309. The position of support member 309 within spring housing 301is adjustable, at least between a first position and a second position,and preferably over a range of positions. In the illustrated embodiment,support member 309 is coupled to at least one positioning rod 311. Thelocation of the positioning rod(s) 311, and therefore the location ofsupport member 309, is controlled by adjustment mechanism 313.Adjustment mechanism 313 is preferably an electro-mechanical system, forexample an electric motor using means such as a set of gears (e.g., aworm gear) to control the position of positioning rod(s) 311.Alternately, mechanism 313 may be a pneumatic positioning system orother positioning system. It should be understood that the invention isnot limited to a specific adjustment mechanism; rather, the systemmerely requires a means of controllably positioning spring supportmember 309.

The location of rear spring support member 309 determines the forceapplied by the spring to spring compression member 305, and thus theresistance encountered by the driver as they attempt to depressaccelerator pedal 101. In accordance with the invention, when apreselected battery pack characteristic associated with battery pack 111and monitored by battery pack management system 113 reaches apredetermined level, the spring preload adjustment controller 115adjusts the position of rear spring support member 309 using mechanism313. For example, when the preselected battery pack characteristicreaches the predetermined level, controller 115 changes the position ofsupport member 309 from that shown in FIG. 3 to the position shown inFIG. 4 in which spring 303 is preloaded, i.e., partially compressed.Compression of spring 303 by the rear spring support member 309immediately increases the force applied by the spring to acceleratorpedal 101, thereby instantly alerting the driver, via the change inpedal force, to the change in the monitored battery characteristic. Thusif the monitored battery pack characteristic is battery pack capacity,and the preload controller 115 is set to preload spring 303 when thebattery pack capacity falls below 15 percent, then the driver isimmediately alerted to the fact that the battery pack capacity hasfallen to a critically low level and that battery charging will berequired soon. The driver is then able to vary their route and/or theirdriving characteristics (e.g., acceleration rate, top speed, applyingpower versus coasting, etc.) in order to insure that they reach theirdestination prior to the battery becoming completely drained. Note thatonce alerted, preferably the driver is able to verify battery packconditions by using the vehicle's gauges and displays that providecritical vehicle parameters such as current battery pack capacity.

It will be appreciated that while battery pack capacity is the preferredbattery pack characteristic that is monitored and used by the preloadcontroller 115 to adjust the compression characteristics of spring 303using rear spring support member 309, other battery pack characteristicsmay also be used. For example, in order to make the monitored parametermore easily understood by the driver, the battery pack capacity may bemodified by the average discharge rate (or the current discharge rate)and the vehicle's efficiency to yield a current available driving range,i.e., the driving range that can be achieved before the battery pack iscompletely drained. Thus rather than preloading spring 303 when thebattery pack reaches a preset capacity, e.g., 15 percent capacity, thespring may be preloaded when the current driving range reaches a presetrange, e.g., 20 miles, thereby providing the driver with acharacteristic that they may feel more comfortable with than the batterycapacity. In such a scenario, once the driver experiences an abruptchange in pedal force they would immediately know that they are limitedto a driving range of approximately 20 miles (or other preset range),the exact range depending upon driving conditions (e.g., speed, flatroads versus hills, ambient temperature, battery age, etc.).

In a modification of the embodiment described above, rather than alterthe spring characteristics between two conditions, unloaded andpreloaded, the preload adjustment controller 115 is configured topreload spring 303 to several different levels based on battery packcapacity or an alternate battery pack characteristic. For example,controller 115 may preload the spring 303 to a first level when thebattery pack capacity falls to 25 percent, and to a second level whenthe battery pack capacity falls to 10 percent. FIG. 5 illustrates springassembly 300 with the rear spring support member 309 positioned in anintermediate location between the unloaded state shown in FIG. 3 and thefully preloaded state shown in FIG. 4. This approach allows the user toreceive one or more warnings before the final, critical warning.Preferably in order to insure that the driver notices the change inpedal force, the spring preloading is sufficient at each state that thedriver is immediately aware of the change.

As noted above, in many EVs the regeneration system is configured tooperate when the driver reduces and/or releases pressure from theaccelerator pedal, and before the driver applies pressure to the brakepedal. It should be understood that the inclusion of regeneration priorto pressure being applied to the brake pedal does not impact the use ofthe embodiment. In such a configuration and as illustrated in FIG. 6,the regeneration system controller 601 would then monitor a vehiclecondition, e.g., position of pedal 101, pressure applied to pedal 101,direction of pedal 101 motion, or other condition, and apply theregeneration system 603 whenever the appropriate conditions are met,e.g., during deceleration, when pressure is released from pedal 101,etc. Since the application of the regeneration system does not affectperformance of the previous embodiment, and as regeneration systems arewell known by those of skill in the art, further discussion is notprovided herein.

In a modification of the embodiment described above, rather thanpreloading spring 303 based on a monitored battery characteristic,preloading is used to distinguish between the regeneration and powerstages of the pedal stroke. In this configuration, when the pedalposition sensor 105 reaches a preselected position corresponding to apreset amount of pedal travel, the system is configured to switchbetween recharging battery pack 111 using regeneration system 603 andapplying power to motor 109. In order to indicate to the driver thischange in operation, controller 115 is configured to preload spring 303at the transition point between stroke stages. Accordingly, when the caris at rest and the driver first depresses pedal 101, the motion of pedal101 is relatively easy as the only resistance is provided by spring 303with no preloading. During this stage of pedal motion, motor controller107 does not supply power to motor 109 and, since the car is not yetmoving, the regeneration system 603 does not generate power to rechargebattery pack 111. Once pedal position sensor 105 detects that the pedalhas reached the transition point between stroke stages, controller 115is configured to preload spring 303 by adjusting the position of rearspring support member 309. After the transition point, as the drivercontinues to apply pressure to pedal 101 they will sense a change inpedal resistance as a result of the preloading of spring 303. Throughoutthe second stroke stage, regardless of whether the driver is depressingor partially releasing pedal 101, motor controller 107 supplies power tomotor 109 and controller 115 continues to preload spring 303. Duringdeceleration and as the driver releases pressure from pedal 101, oncepedal position sensor 105 detects that the pedal has reached thetransition point, controller 115 returns the rear support member 309 tothe non-preloaded position, allowing the driver to sense the change inpedal stroke by noting the difference in pedal resistance. During thisstage and with spring preloading deactivated, the regeneration systemcontroller 601 actively recharges battery pack 111 using regenerationsystem 603. After the driver releases all pressure from pedal 101, thesystem can be configured to either stop or continue recharging batterypack 111 for as long as the car is still moving.

Preferably the preset or presets used by the preload adjustmentcontroller 115 to determine when to preload the spring assembly areinput by the vehicle manufacturer. Alternately, the system can beconfigured to allow a third party, such as a service technician, inputor adjust the preload presets. Alternately, the system can be configuredto allow the end user to input or adjust the preload presets. Allowingthe end user to input or adjust the preload presets permits a more riskadverse driver, for example a new EV owner, to set-up the preload presetto a relatively high battery pack capacity (or similar characteristic)while permitting a less risk adverse driver, for example an experiencedEV owner or an EV owner that has easy access to multiple chargingstations throughout their driving area, to use a preload preset set at arelatively low battery pack capacity (or similar characteristic).Allowing the end user to set the preload presets is also more convenientwhen the vehicle is used by multiple drivers, for example the members ofa family. An end user may also wish to change the preload preset beforeusing the vehicle for vacation travel in an unknown area where chargingstation location and access is unknown.

FIG. 7 illustrates the system shown in FIG. 6, modified to include auser interface 701. User interface 701, which is preferably integratedinto the vehicle's management system, may use a touch-sensitive display,a non-touch-sensitive display combined with any of a variety of switchtypes (e.g., toggle switches, push button switches, slide switches,etc.), a stand-alone switch (e.g., slide switch, rotary switch, etc.)with several different presets from which to select, or other means thatallow the user to select the desired preload preset. It should beunderstood that the inclusion of a user interface that allows a user toset the preload preset may also be included in the system shown in FIG.1, or other systems that utilize the accelerator spring assembly of theinvention.

FIGS. 8 and 9 illustrate a preferred embodiment of the invention using adual stage spring assembly 800 in which one of the stages may bepreloaded. This embodiment allows the accelerator pedal system tocommunicate at least two different vehicle operating conditions to thedriver, plus notify the driver of a critical operating condition, suchas a low battery capacity, via spring preloading.

In dual stage spring assembly 800, two different springs 801 and 803 arecontained within spring housing 805. The two springs 801 and 803 exhibitdifferent spring characteristics, specifically different levels ofspring force, that are easily distinguishable by the driver as he or sheapplies pressure to pedal 101. As in the prior embodiment, preferablysprings 801 and 803 are each comprised of a compression coil spring asshown, although other types of springs may be used. Accelerator pedalarm 201, attached at one end to pedal 101, passes into spring housing805 and is coupled to a spring compression member 807, distal from pedal101.

In the preferred and illustrated embodiment, when the driver initiallyapplies pressure to pedal 101, the weaker spring compresses. In thisembodiment the weaker spring is spring 801. If the driver continues toexert pressure on pedal 101 after spring 801 is completely compressed inregion 809, or at the point at which the force exerted by spring 801exceeds the force exerted by spring 803, then secondary springcompression member 811 will begin to compress spring 803. Note that inthis embodiment a pair of stops 813 and 815 limit motion of springcompression member 811 to region 817.

In the preferred mode of operation, when the car is at rest and thedriver first depresses pedal 101, the motion of pedal 101 is relativelyeasy as the only resistance is provided by weak spring 801. During thisstage of pedal motion, motor controller 107 does not supply power tomotor 109 and, since the car is not yet moving, the regeneration system603 does not generate power to recharge battery pack 111. After spring801 is fully compressed, as the driver continues to apply pressure topedal 101 they will sense a change in pedal resistance as a result ofstrong spring 803. Throughout the compression range 817 of spring 803,regardless of whether the driver is depressing or partially releasingpedal 101, motor controller 107 supplies power to motor 109. Duringdeceleration if the driver continues to release pressure on pedal 101,the driver is able to sense the difference in pedal resistance betweenregions 817 and 809 of the spring assembly. Once secondary springcompression member 811 reaches stops 813, pedal resistance drops and theregeneration system controller 601 actively recharges battery pack 111using regeneration system 603 throughout region 809. After the driverreleases all pressure from pedal 101, the system can be configured toeither stop or continue recharging battery pack 111 for as long as thecar is still moving.

In at least one embodiment of the invention, when spring 801 is fullycompressed and the secondary spring compression member 811 is at rest onstops 813, i.e., when the spring assembly is between ranges 809 and 817,the car coasts. Thus the present invention allows a third mode ofoperation, i.e., coasting, to be easily sensed, and thus controlled, bythe driver. Coasting allows the driver to extend the distance the cartravels for a given amount of energy stored within battery pack 111. Itwill be appreciated that in some situations coasting may be preferredwhile in other situations, for example when the battery pack has a lowcharge level, charging via the regeneration system may be preferred.

The front face of spring 803 rests against secondary spring compressionmember 811 while the rear face of spring 803 rests against a rear springsupport member 819. The position of support member 819 within springhousing 805 is adjustable, at least between a first position (see FIG.8) and a second position (see FIG. 9), and in some applications over arange of positions as described above relative to the embodiment shownin FIG. 5. In the embodiment shown in FIGS. 8 and 9, support member 819is coupled to at least one positioning rod 821. The location of thepositioning rod(s) 821, and therefore the location of support member819, is controlled by adjustment mechanism 823. Adjustment mechanism 823may be an electro-mechanical system, a pneumatic positioning system orother positioning system. It should be understood that the invention isnot limited to a specific adjustment mechanism; rather, the systemmerely requires a means of controllably positioning spring supportmember 819.

The location of rear spring support member 819 determines the forceapplied by spring 803 to the secondary spring compression member 811,and thus the resistance encountered by the driver as they depressaccelerator pedal 101 within the second stage 817 of the pedal stroke,e.g., the accelerator portion versus the regeneration portion of thestroke. As in the prior embodiment, when a preselected battery packcharacteristic associated with battery pack 111 and monitored by batterypack management system 113 reaches a predetermined level, the springpreload adjustment controller 115 adjusts the position of rear springsupport member 819 using mechanism 823, thereby compressing andpreloading spring 803. As a result of preloading spring 803, as thedriver depresses pedal 101 past the regeneration stage (region 809), orif the pedal stroke has already traveled past the regeneration stage,then the driver will be immediately alerted to the change in themonitored battery pack characteristic (e.g., current battery packcapacity, current available driving range, etc.). Once the driver hasbeen alerted to the fact that the battery pack capacity (or othercharacteristic) has fallen to a critically low level, appropriate actioncan be taken such as varying the travel route and/or drivingcharacteristics (e.g., acceleration rate, top speed, applying powerversus coasting, etc.). As in the previously described embodimentillustrated in FIGS. 3-5, the preset(s) used to determine when toinitiate spring preloading may be set by the vehicle's manufacturer, athird party or even the driver utilizing user interface 701.

FIG. 10 illustrates a preferred embodiment of the invention using a dualstage spring assembly 1000 in which the transition point between the twostages may be adjusted. As in the embodiment illustrated in FIGS. 8 and9, during the first stage of pedal motion regeneration system 603actively recharges battery pack 111, assuming the vehicle is in motion,while in the second stage of pedal motion power is supplied to motor109. In at least one configuration of this embodiment, and as describedabove relative to the previous embodiment, the system allows the car tocoast when the pedal is located between the first and second stages.

In dual stage spring assembly 1000, two different springs 1001 and 1003are contained within spring housing 1005. The two springs 1001 and 1003exhibit different spring characteristics, specifically different levelsof spring force, thereby allowing the driver to distinguish between thefirst and second stages of pedal motion. As in the prior embodiments,preferably springs 1001 and 1003 are each comprised of a compressioncoil spring as shown, although other types of springs may be used.Accelerator pedal arm 201, attached at one end to pedal 101, passes intospring housing 1005 and is coupled to a spring compression member 1007,distal from pedal 101.

In the preferred and illustrated embodiment, when the driver initiallyapplies pressure to pedal 101, the weaker spring is compressed. FIG. 11illustrates spring assembly 1000 with a partial depression of pedal 101,causing weaker spring 1001 to be partially compressed by springcompression member 1007. If the driver increases the pressure on pedal101, thereby further depressing pedal 101, spring 1001 will becomecompletely compressed within region 1009. Further depression of pedal101 will then cause spring compression member 1007 to compress spring1003. In the illustrated embodiment, spring compression member 1007indirectly compresses spring 1003 using secondary spring compressionmember 1011. Note that a guide 1013 is preferably used to guidesecondary spring compression member 1011 and to insure proper placementof spring 1003 within container 1005. FIG. 12 illustrates springassembly 1000 with pedal 101 sufficiently depressed to cause completecompression of spring 1001 within region 1009 and partial compression ofspring 1003 within region 1015.

In the preferred mode of operation, when the car is at rest and thedriver first depresses pedal 101, the motion of pedal 101 is relativelyeasy as the only resistance is provided by weak spring 1001. During thisstage of pedal motion, motor controller 107 does not supply power tomotor 109 and, since the car is not yet moving, the regeneration system603 does not generate power to recharge battery pack 111. After spring1001 is fully compressed, the driver is able to sense the difference inspring force indicative of the change between the first and secondstages of pedal operation. If the driver increases the pressure appliedto pedal 101 and depresses pedal 101 further, the spring force from thecombination of springs 1001 and 1003 will increase pedal resistance.Throughout compression range 1015, regardless of whether the driver isactively depressing or partially releasing pedal 101, motor controller107 supplies power to motor 109. During deceleration if the drivercontinues to release pressure on pedal 101, the driver is able to sensethe difference in pedal resistance between regions 1015 and 1009 of thespring assembly. After spring compression member 1007 is no longerapplying pressure to spring 1003, either directly or indirectly as shownin the preferred embodiment, power is no longer supplied to motor 109and the regeneration system controller 601 actively recharges batterypack 111 using regeneration system 603. After the driver releases allpressure from pedal 101, the system can be configured to either stop orcontinue recharging battery pack 111 for as long as the car is stillmoving.

The embodiment illustrated in FIGS. 10-12 can be configured to provide athird mode of operation, specifically coasting. By applying this mode ofoperation between stages 1009 and 1015, i.e., once spring 1001 is fullycompressed and compression of spring 1003 has not yet begun, the driveris able to easily select between the three modes of operation; power,coasting and regeneration. As previously noted, by foregoing batteryrecharging via the regeneration system and coasting, the driver is ableto extend the distance the car travels for a given amount of energystored within battery pack 111.

In the embodiment shown in FIGS. 10-12, the user is able to adjust thepoint at which the pedal assembly switches between the first stage andthe second stage of operation. In particular, the user is able toshorten or lengthen region 1009, and thus the amount of pedal motionassociated with the regeneration system. This aspect is illustrated inFIG. 13. As shown, the position of spring 1003 relative to springcompression member 1007 has been changed, reducing the size of region1009 to new size 1009′. As a result of this change, pedal 101 is onlydepressed a relatively short distance before the second stage (i.e.,spring 1003) is engaged. This aspect of the invention allows furthercustomization of the accelerator pedal motion and thus customization ofthe driving experience.

Spring assembly 1000 includes a second spring subassembly that includesspring 1003, rear spring support member 1017, spring guide 1013 and thesecondary spring compression member 1011, assuming a secondary springcompression member is used as preferred. The position of rear springsupport member 1017 and the entire second spring subassembly withinspring housing 1005 is adjustable. Rear spring support member 1017, andtherefore the entire second spring subassembly, is coupled to at leastone positioning rod 1019. The location of the positioning rod(s) 1019,and therefore the location of support member 1017 and the second springsubassembly, is controlled by adjustment mechanism 1021. Adjustmentmechanism 1021 may be an electro-mechanical system, a pneumaticpositioning system or other positioning system. It should be understoodthat the invention is not limited to a specific adjustment mechanism;rather, the system merely requires a means of controllably positioningthe second spring subassembly.

As described above, the position of the second spring subassembly withinspring housing 1005 determines the length of the pedal stroke withinregion 1009, and therefore the amount of the pedal stroke dedicated tothe regeneration system rather than motor control. The location ofspring support member 1017 and the second spring assembly is determinedby positioning mechanism 1021 which, in turn, is determined by stagetransition controller 1023. As shown in FIG. 14, the stage transitioncontroller 1023 is coupled to the accelerator spring assembly 103, andmore specifically to positioning mechanism 1021 of accelerator springassembly 103 as described above. A user interface 701, which is coupledto stage transition controller 1023, allows the transition point betweenthe first and second stages to be adjusted after the vehicle ismanufactured, for example by the driver, thereby allowing the driver tocustomize the accelerator pedal stroke. User interface 701, which ispreferably integrated into the vehicle's management system, may use atouch-sensitive display, a non-touch-sensitive display combined with anyof a variety of switch types (e.g., toggle switches, push buttonswitches, slide switches, etc.), a stand-alone switch (e.g., slideswitch, rotary switch, etc.) with several different presets from whichto select, or other means that allow the user to select the desiredtransition point between the first and second stages.

FIGS. 15-18 illustrate a preferred embodiment of the invention using adual stage spring assembly 1500 in which either, or both, springs may bepreloaded. This embodiment allows the accelerator pedal system tocommunicate at least two different vehicle operating conditions to thedriver, plus notify the driver of two different critical operatingconditions via spring preloading of two different springs within theassembly. Preferably, and as in the embodiments illustrated in FIGS.8-13, during the first stage of pedal motion regeneration system 603actively recharges battery pack 111, assuming the vehicle is in motion,while in the second stage of pedal motion power is supplied to motor109. In at least one configuration of this embodiment, and as describedabove relative to the previous embodiments, the system allows the car tocoast when the pedal is located between the first and second stages.

In dual stage spring assembly 1500, two different springs 1501 and 1503are contained within spring housing 1505. The two springs 1501 and 1503exhibit different spring characteristics, specifically different levelsof spring force, thereby allowing the driver to distinguish between thefirst and second stages of pedal motion. As in the prior embodiments,preferably springs 1501 and 1503 are each comprised of a compressioncoil spring as shown, although other types of springs may be used.Accelerator pedal arm 201, attached at one end to pedal 101, passes intospring housing 1505 and is coupled to a spring compression member 1507,distal from pedal 101.

In the preferred and illustrated embodiment, when the driver initiallyapplies pressure to pedal 101, weaker spring 1501 is compressed byspring compression member 1507. If the driver increases the pressure onpedal 101, thereby further depressing pedal 101, spring 1501 will becomecompletely compressed within region 1509. Further depression of pedal101 will then cause spring compression member 1507 to compress spring1503. In the illustrated embodiment, spring compression member 1507indirectly compresses spring 1503 using secondary spring compressionmember 1511. Note that a guide 1513 is preferably used to guidesecondary spring compression member 1511 and to insure proper placementof spring 1503 within container 1505. Although not shown, stops may beused to limit the range of motion of pedal 101, and thus the range ofcompression of the springs within spring housing 1505. The stops may beincorporated into pedal arm 201, or within spring housing 1505.

In the preferred mode of operation, when the car is at rest and thedriver first depresses pedal 101, the motion of pedal 101 is relativelyeasy as the only resistance is provided by weak spring 1501. During thisstage of pedal motion, motor controller 107 does not supply power tomotor 109 and, since the car is not yet moving, the regeneration system603 does not generate power to recharge battery pack 111. After spring1501 is fully compressed, the driver is able to sense the difference inspring force indicative of the change between the first and secondstages of pedal operation. If the driver increases the pressure appliedto pedal 101 and depresses pedal 101 further, the spring force from thecombination of springs 1501 and 1503 will increase pedal resistance.Throughout compression range 1515, regardless of whether the driver isactively depressing or partially releasing pedal 101, motor controller107 supplies power to motor 109. During deceleration if the drivercontinues to release pressure on pedal 101, the driver is able to sensethe difference in pedal resistance between regions 1515 and 1509 of thespring assembly. After spring compression member 1507 is no longerapplying pressure to spring 1503, either directly or indirectly as shownin the preferred embodiment, power is no longer supplied to motor 109and the regeneration system controller 601 actively recharges batterypack 111 using regeneration system 603. After the driver releases allpressure from pedal 101, the system can be configured to either stop orcontinue recharging battery pack 111 for as long as the car is stillmoving.

The embodiment illustrated in FIGS. 15-18 can be configured to provide athird mode of operation, specifically coasting. By applying this mode ofoperation between stages 1509 and 1515, i.e., once spring 1501 is fullycompressed and compression of spring 1503 has not yet begun, the driveris able to easily select between the three modes of operation; power,coasting and regeneration. As previously noted, by foregoing batteryrecharging via the regeneration system and coasting, the driver is ableto extend the distance the car travels for a given amount of energystored within battery pack 111.

Unlike the embodiment illustrated in FIGS. 8 and 9 in which only one ofthe springs in the spring assembly may be preloaded, in the embodimentillustrated in FIGS. 15-18 either or both of the springs in the springassembly may be preloaded, thus allowing additional information to beprovided to the driver via differences in pedal return force.

FIG. 16 illustrates the technique used to preload spring 1501. The frontface of spring 1501 rests against spring compression member 1507 whilethe rear face of spring 1501 rests against a rear spring support member1517. The position of support member 1517 within spring housing 1505 isadjustable, at least between a first position (see FIG. 15) and a secondposition (see FIG. 16), and in some applications over a range ofpositions. In the embodiment shown in FIGS. 15 and 16, support member1517 is coupled to at least one, and preferably multiple positioningrods 1519. The location of positioning rods 1519, and therefore thelocation of rear spring support member 1517, is controlled by adjustmentmechanism 1521. Controller 1523 determines whether or not to preloadspring 1501 and, at least in some embodiments, the level of preloadingto be applied to spring 1501. Adjustment mechanism 1521 may be anelectro-mechanical system, a pneumatic positioning system or otherpositioning system. It should be understood that the invention is notlimited to a specific adjustment mechanism; rather, the system merelyrequires a means of controllably positioning spring support member 1517.

The location of rear spring support member 1517 determines the forceapplied by spring 1501 to the spring compression member 1507, and thusthe resistance encountered by the driver as they depress acceleratorpedal 101 within the first stage 1509 of the pedal stroke. Although notrequired, preferably this stage 1509 of the pedal stroke corresponds tothe regeneration portion of the stroke. Any of a variety of monitoredcharacteristics may be used to determine when to preload spring 1501using rear spring support member 1517. For example, spring 1501preloading may be used to indicate a characteristic of the regenerationsystem such as a different level of regeneration, regardless of whetherthe level of regeneration is user selected or vehicle selected based onbattery needs. Alternately, spring 1501 preloading may be used toindicate that a battery pack characteristic, such as the current batterylevel, has fallen below (or exceeded) a preset level. Alternately,spring 1501 preloading may be used to alert the driver of a system orsubsystem error (e.g., battery pack malfunction, battery overheating,regeneration system malfunction, etc.).

FIG. 17 illustrates the technique used to preload spring 1503. Thelocation of rear spring support member 1525 determines the force appliedby spring 1503 to the secondary spring compression member 1511, and thusthe resistance encountered by the driver as they depress acceleratorpedal 101 within the second stage 1515 of the pedal stroke, e.g., theaccelerator portion versus the regeneration portion of the stroke. Theposition of rear spring support member 1525 relative to secondary springcompression member 1511 is adjustable. Rear spring support member 1525is coupled to at least one positioning rod 1527. The location of thepositioning rod(s) 1527, and therefore the location of rear springsupport member 1525, is controlled by adjustment mechanism 1529.Adjustment mechanism 1529 may be an electro-mechanical system, apneumatic positioning system or other positioning system. It should beunderstood that the invention is not limited to a specific adjustmentmechanism; rather, the system merely requires a means of controllablypositioning the second spring subassembly.

Although any of a variety of monitored characteristics may be used todetermine when to preload spring 1503 using rear spring support member1525, preferably a battery characteristic such as current batterycapacity or current available driving range is used. As such, when thepreselected characteristic, for example a battery pack characteristicmonitored by battery pack management system 113, reaches a predeterminedlevel, then second spring preload adjustment controller 1531 adjusts theposition of rear spring support member 1525 using mechanism 1529,thereby compressing and preloading spring 1503. As a result ofpreloading spring 1503, as the driver depresses pedal 101 past theregeneration stage (region 1509), or if the pedal stroke has alreadytraveled past the regeneration stage, then the driver will beimmediately alerted to the change in the monitored battery packcharacteristic (e.g., current battery pack capacity, current availabledriving range, etc.). Once the driver has been alerted to the fact thatthe battery pack capacity (or other characteristic) has fallen to acritically low level, appropriate action can be taken such as varyingthe travel route and/or driving characteristics (e.g., accelerationrate, top speed, applying power versus coasting, etc.).

An advantage of the present embodiment is that springs 1501 and 1503 maybe preloaded independently of one another. Additionally, either onespring or both springs may be preloaded. FIG. 18 illustrates theembodiment with both springs 1501 and 1503 preloaded. FIG. 19 provides asystem schematic of the dual stage spring assembly shown in FIGS. 15-18.While the spring preload adjustment controllers are typically onlycoupled to those systems that monitor the characteristic being used todetermine when to preload the corresponding spring, in the embodimentillustrated in FIG. 19, both spring preload adjustment controllers arecoupled to both the battery pack management system 113 and theregeneration system controller 601, thus adding versatility to thespring preload controllers. A user interface 701 may be coupled to thespring preload adjustment controllers as shown in FIG. 20, therebyallowing the driver to adjust the spring preload subsystems. Aspreviously noted, user interface 701 may use a touch-sensitive display,a non-touch-sensitive display combined with any of a variety of switchtypes (e.g., toggle switches, push button switches, slide switches,etc.), a stand-alone switch (e.g., slide switch, rotary switch, etc.)with several different presets from which to select, or other means thatallow the user to preset the preload characteristics for springs 1501and 1503.

In at least one embodiment of the invention, the ability to alter thetransition point between the first and second stages of acceleratorpedal stroke may be combined with the ability to preload one or bothsprings in the spring assembly. For example, FIGS. 21 and 22 illustratethe combination of the system that allows adjustment of the point atwhich the pedal assembly switches between the first and second stages ofoperation as shown in FIGS. 10 and 13 with a first spring preloadingsystem as illustrated in FIGS. 15 and 16. FIG. 21 illustrates thisembodiment with no preloading of spring 1501 and with the first stage ofpedal motion maximized while FIG. 22 illustrates the same embodimentwith spring 1501 preloaded and the first stage of pedal motionshortened. It should be understood that spring 1501 may be preloadedwithout altering the length of the first stage of pedal motion and,similarly, the first stage of pedal motion may be shortened withoutpreloading spring 1501.

FIGS. 23 and 24 illustrate a system combination that allows adjustmentof the point at which the pedal assembly switches between the first andsecond stages of operation as shown in FIGS. 10 and 13 with a secondspring preloading system as illustrated in FIGS. 15 and 17. FIG. 23illustrates this embodiment with no preloading of spring 1503 and withthe first stage of pedal motion maximized while FIG. 24 illustrates thesame embodiment with spring 1503 preloaded and the first stage of pedalmotion shortened. In this embodiment the second spring assembly includesspring 1503, rear spring support member 1525, rear second springassembly support member 2301, spring guide 1513 and the secondary springcompression member 1511. The position of the entire second springsubassembly within spring housing 1505 is adjustable by moving springassembly support member 2301 using positioning member 2303 andadjustment mechanism 1021. The position of rear spring support member1525 within the second spring subassembly and relative to secondaryspring compression member 1511, and thus the amount of spring preloadingimparted to spring 1503, is adjustable via positioning rod(s) 1527 andadjustment mechanism 1529. It should be understood that spring 1503 maybe preloaded without altering the length of the first stage of pedalmotion and, similarly, the first stage of pedal motion may be shortenedwithout preloading spring 1503.

FIGS. 25 and 26 illustrate a system embodiment that allows adjustment ofthe point at which the pedal assembly switches between the first andsecond stages of operation as shown in FIGS. 10, 13, 22 and 24 with afirst spring preloading system as shown in FIGS. 15, 16 and 22 and asecond spring preloading system as illustrated in FIGS. 15, 17 and 24.FIG. 25 illustrates this embodiment with the first stage of pedal motionmaximized and with no preloading of either spring 1501 or spring 1503.FIG. 26 illustrates the same embodiment with the first stage of pedalmotion shortened and both spring 1501 and spring 1503 preloaded. Itshould be understood that spring 1501 may be preloaded without alteringthe length of the first stage of pedal motion and/or preloading spring1503; that spring 1503 may be preloaded without altering the length ofthe first stage of pedal motion and/or preloading spring 1501; and thatthe first stage of pedal motion may be shortened without preloadingeither or both springs 1501 and 1503.

FIGS. 27 and 28 illustrate an alternate embodiment of the invention thatoffers the advantages of the previously described accelerator assembliesin a more versatile system. In assembly 2700, a positioning mechanism2701 coupled to a drive system 2703 is used to vary the resistanceapplied to pedal linkage arm 201, and thus the return force applied topedal 101 and felt by the driver as they depress and release theaccelerator pedal. Positioning mechanism 2701 may be mechanical, forexample a simple screw mechanism, in which case the force applied tolinkage arm 201 via mechanism 2701 is supplied by a motor 2703.Alternately, positioning mechanism 2701 may be comprised of a pistonassembly and drive system 2703 may be comprised of a hydraulic orpneumatic pump with a hydraulic or pneumatic reservoir. Controller 2705determines the amount of force to be applied by positioning mechanism2701 and driver 2703 to pedal linkage arm 201 and pedal 101.

In the illustrated embodiment, the assembly is contained with a housing2707 which can provide a guide for positioning mechanism 2701. Attachedto mechanism 2701 is a spring compression member 2709, which may be inthe form of a ring surrounding mechanism 2701. Interposed betweencompression member 2709 and inner assembly surface 2711 is a spring2713. As in the prior embodiments, preferably spring 2713 is comprisedof a compression coil spring as shown, although other types of springsmay be used. Spring 2713 applies a nominal return force to linkage arm201 and pedal 101, thereby insuring that even if drive system 2703malfunctions, return force is applied to pedal 101 and the risk ofunintentional vehicle acceleration is avoided. In the illustratedembodiment, inner surface 2715 of housing 2707 provides a pedal stop,limiting outward motion of spring compression member 2709.

In a preferred mode of operation utilizing assembly 2700, when the caris at rest and the driver first depresses pedal 101, the motion of pedal101 is relatively easy as subassembly 2701/2703 is preferably configuredto apply little return force during the initial pedal stroke and spring2713 is a relatively weak spring. During this stage of pedal motion,motor controller 107 does not supply power to motor 109 and, since thecar is not yet moving, the regeneration system 603 does not generatepower to recharge battery pack 111. After the pedal has reached a presetlevel of travel as determined by pedal position sensor 105, where sensor105 is preferably integrated into assembly 2700, pedal load controller2705 increases the return force applied to pedal 101 to a sufficientdegree to insure that the driver is immediately able to sense thedifference in force indicative of a change between a first stage and asecond stage of pedal operation. If the driver continues to depresspedal 101 after this transition point, then she will experience anincrease in pedal resistance. At the transition point between the firstand second pedal strokes, the system is configured to de-activate theregeneration system and to supply power to motor 109. Throughout thisstage of pedal movement, regardless of whether the driver is activelydepressing or partially releasing pedal 101, motor controller 107supplies power to motor 109. The system continually monitors pedalposition via sensor 105 so that once the pedal has traveled sufficientlybackwards towards the driver as the driver releases pressure on pedal101, pedal load controller modifies the return force applied bysubassembly 2701/2703 back to its stage one level. Once again, thedriver is able to immediately detect the difference in pedal resistance,indicating that power is no longer being supplied to motor 109 and thatthe regeneration system controller 601 is actively recharging batterypack 111 using regeneration system 603. After the driver releases allpressure from pedal 101, the system can be configured to either stop orcontinue recharging battery pack 111 for as long as the car is stillmoving.

The transition point between the first and second stages of pedal motionis determined by the point at which pedal load controller 2705 modifiesthe return force applied by subassembly 2701/2703. This transition pointmay be preset by the manufacturer or its agents (e.g., servicetechnician) and as such, the system will utilize a configuration such asthat illustrated in FIG. 29. In at least one embodiment, and asillustrated in FIG. 30, a user interface 701 is coupled to pedal loadcontroller 2705. User interface 701 provides a means for the user toadjust the point at which the pedal assembly switches between the firststage and the second stage of operation and, as a result, allows theuser to shorten or lengthen the amount of pedal motion associated withthe regeneration system.

As in prior embodiments, assembly 2700 can be configured to provide athird mode of operation, specifically coasting. In this configuration,when sensor 105 determines that the pedal has been depressed to thetransition point between the first and second stages of operation,regardless of whether the transition point is set by the vehiclemanufacturer, a third party or the user, the system allows a third modeof operation, i.e., coasting. During coasting, and as previouslydescribed, power is neither supplied to motor 109 nor is theregeneration system active. As previously noted, by foregoing batteryrecharging via the regeneration system and coasting, the driver is ableto extend the distance the car travels for a given amount of energystored within battery pack 111.

Pedal load controller 2705 may also be used to communicate a change in amonitored vehicle condition, such as the battery level dropping below apreset capacity, or the available driving range dropping below a presetrange, or a battery pack malfunction, or a regeneration systemmalfunction, or other information. The preset condition used to triggerthe pedal load controller 2705, thereby causing a detectable change inpedal resistance, may be set-up by the vehicle manufacturer or by theuser utilizing user interface 701. Preferably if the user is allowed toalter the preset, they are provided with several different options. Forexample, the system may allow the user to select the pre-set batterypack condition that triggers modifying return force from severalconditions (e.g., battery pack capacity, driving range, batterymalfunction, etc.), and/or select the value for the selected conditionthat triggers modifying return force from multiple values (e.g., 10percent, 15 percent, 20 percent, 25 percent battery pack capacity), thusallowing the system to be customized to match an individual driver'spreferences.

It should be understood that load controller 2705 can modify returnforce/pedal resistance at any time during the pedal stroke, i.e., eitherprior to depression of pedal 101 or after the pedal has been partiallydepressed. As a result, assembly 2700 may communicate a criticalcondition (e.g., low battery pack level, short available driving range,system malfunction, etc.) at any time to the driver. Furthermore, sincepedal load controller 2705 can modify return force over a wide range,then assembly 2700 may be configured to change pedal resistance in orderto denote a change in driving mode (e.g., applying power to motor 109,recharging battery 111 using regeneration system 603, coasting); todenote a change in a monitored vehicle condition (e.g., battery packlevel, available driving range, malfunction, etc.); or to denote both.

Although simple spring preloading is described above relative to thevarious preferred embodiments, the spring preloading system of theinvention may also communicate a critical condition (e.g., low batterypack level, short available driving range, system malfunction, etc.) bypulsing the preload controller, thus causing pedal 101 to vibrate,thereby alerting the driver of a detected problem. Furthermore, whilepreferred spring assembly configurations have been illustrated anddescribed, it will be appreciated that other configurations, for exampleusing a different type of spring or spring housing, may also be usedwithout changing the functionality and approach described relative toeach of these embodiments.

Spring assembly systems and methods of operation have been described ingeneral terms as an aid to understanding details of the invention. Insome instances, well-known structures, materials, and/or operations havenot been specifically shown or described in detail to avoid obscuringaspects of the invention. In other instances, specific details have beengiven in order to provide a thorough understanding of the invention. Oneskilled in the relevant art will recognize that the invention may beembodied in other specific forms, for example to adapt to a particularvehicle configuration or spring type or vehicle application or materialor component, without departing from the spirit or essentialcharacteristics thereof. Therefore the disclosures and descriptionsherein are intended to be illustrative, but not limiting, of the scopeof the invention.

What is claimed is:
 1. A dual stage vehicle pedal accelerator assembly, comprising: an accelerator pedal; and a spring assembly, wherein an accelerator linkage arm couples said accelerator pedal to said spring assembly, said spring assembly comprising: a first spring; a first spring compression member coupled to said accelerator linkage arm, wherein said first spring compression member is proximate to a first end of said first spring; a second spring; a second spring compression member, wherein said second spring compression member is interposed between a second end of said first spring and a first end of said second spring; a rear spring support member proximate to a second end of said second spring, said rear spring support member positionable in at least a first position and a second position, wherein said rear spring support member in said second position increases preload compression of said second spring compared to said first position, and wherein said rear spring support member in said second position increases accelerator pedal resistance compared to said first position; an adjustment mechanism coupled to said rear spring support member, wherein upon receipt of a first control signal said adjustment mechanism is configured to move said rear spring support member to said first position, and wherein upon receipt of a second control signal said adjustment mechanism is configured to move said rear spring support member to said second position; and a preload adjustment controller coupled to said adjustment mechanism, said preload adjustment controller configured to transmit said first and second control signals to said adjustment mechanism.
 2. The dual stage vehicle pedal accelerator assembly of claim 1, further comprising a battery pack management system coupled to a vehicle battery pack and to said preload adjustment controller, wherein said battery pack management system monitors at least one characteristic of said vehicle battery pack, wherein said preload adjustment controller transmits said first control signal to said adjustment mechanism when said at least one characteristic of said vehicle battery pack is within a preset range, and wherein said preload adjustment controller transmits said second control signal to said adjustment mechanism when said at least one characteristic of said vehicle battery pack is outside of said preset range.
 3. The dual stage vehicle pedal accelerator assembly of claim 2, wherein said at least one characteristic of said vehicle battery pack corresponds to a current battery pack capacity.
 4. The dual stage vehicle pedal accelerator assembly of claim 2, wherein said at least one characteristic of said vehicle battery pack corresponds to an available driving range based on a current battery pack capacity.
 5. The dual stage vehicle pedal accelerator assembly of claim 2, wherein said at least one characteristic of said vehicle battery pack corresponds to a current battery pack temperature.
 6. The dual stage vehicle pedal accelerator assembly of claim 2, wherein said preset range is input by a vehicle manufacturer.
 7. The dual stage vehicle pedal accelerator assembly of claim 2, further comprising a user interface coupled to said preload adjustment controller, wherein said preset range is input into said preload adjustment controller via said user interface.
 8. The dual stage vehicle pedal accelerator assembly of claim 2, said rear spring support member positionable in at least a third position, wherein said rear spring support member in said third position increases accelerator pedal resistance compared to said first position and decreases accelerator pedal resistance compared to said second position, wherein upon receipt of a third control signal said adjustment mechanism is configured to move said rear spring support member to said third position, and wherein said preload adjustment controller is configured to transmit said third control signal to said adjustment mechanism when said at least one characteristic of said vehicle battery pack falls below a preset level.
 9. The dual stage vehicle pedal accelerator assembly of claim 1, wherein said first spring is comprised of a compression coil spring.
 10. The dual stage vehicle pedal accelerator assembly of claim 1, wherein said second spring is comprised of a compression coil spring.
 11. The dual stage vehicle pedal accelerator assembly of claim 1, wherein a first spring force corresponding to said first spring is less than a second spring force corresponding to said second spring.
 12. The dual stage vehicle pedal accelerator assembly of claim 1, further comprising at least one positioning member, wherein said at least one positioning member couples said adjustment mechanism to said rear spring support member.
 13. The dual stage vehicle pedal accelerator assembly of claim 1, wherein said adjustment mechanism is comprised of an electro-mechanical system.
 14. The dual stage vehicle pedal accelerator assembly of claim 13, wherein said an electro-mechanical system is comprised of an electric motor.
 15. The dual stage vehicle pedal accelerator assembly of claim 1, wherein said adjustment mechanism is comprised of a pneumatic positioning system.
 16. The dual stage vehicle pedal accelerator assembly of claim 1, further comprising: a regeneration system coupled to a vehicle battery pack, said regeneration system configured to recharge said vehicle battery pack when activated; a pedal stroke position sensor, wherein said pedal stroke position sensor monitors travel of said accelerator pedal and detects an initial stage of accelerator pedal travel corresponding to a first pedal stroke stage and detects a final stage of accelerator pedal travel corresponding to a second pedal stroke stage; and a regeneration system controller coupled to said pedal stroke position sensor and to said regeneration system, said regeneration system controller configured to activate said regeneration system during said first pedal stroke stage and configured to deactivate said regeneration system during said second pedal stroke stage.
 17. The dual stage vehicle pedal accelerator assembly of claim 16, wherein during said second pedal stroke stage said vehicle battery pack is electrically coupled to a vehicle propulsion motor.
 18. The dual stage vehicle pedal accelerator assembly of claim 17, said regeneration system controller further configured to deactivate said regeneration system after completion of said first pedal stroke stage and prior to initiation of said second pedal stroke stage.
 19. The dual stage vehicle pedal accelerator assembly of claim 16, wherein during accelerator pedal motion within said first pedal stroke stage said first spring compression member moves and said second spring compression member remains stationary, and wherein during accelerator pedal motion within said second pedal stroke stage said first spring compression member moves and said second spring compression member moves.
 20. The dual stage vehicle pedal accelerator assembly of claim 1, further comprising an accelerator pedal stop, wherein said accelerator pedal stop limits accelerator pedal travel.
 21. The dual stage vehicle pedal accelerator assembly of claim 1, further comprising a spring housing, wherein said first spring and said second spring are contained within said spring housing.
 22. The dual stage vehicle pedal accelerator assembly of claim 21, further comprising a stop integrated into said spring housing, wherein said stop limits travel of said second spring compression member within said spring housing. 